1. Field of the Invention
This invention relates to a ferromagnetic thin film suitable for magnetic heads used in high-density recording on magnetic tapes, magnetic disks or the like, and a method of manufacturing the same.
2. Description of the Prior Art
In recent years, with an improvement in high-density recording on magnetic tapes, magnetic disks or the like, coercive force (Hc) of recording mediums has been more and more increasing. In metal thin-film mediums, those having a coercive force (Hc) of 1,000 Oe or more have been put into practical use. Meanwhile, in order to achieve good recording performances well making the most of the characteristics of magnetic recording mediums having such a coercive force, it is required for magnetic heads to have a high saturation flux density and also to have both a high permeability and a low coercive force also when reproduction is carried out using the same magnetic head. In addition, corrosion resistance, thermal resistance, etc. also must be taken into account as important factors. Vertical magnetic recording systems in which recording is performed by magnetizing a magnetic recording medium not in its longitudinal direction but in its thickness direction have also being put into practical use. In this instance, the end portion of main magnetic pole of a magnetic head must be not larger than 0.5 .mu.m in thickness and hence a magnetic head having a high saturation flux density is required in order to also perform recording in a magnetic recording medium having a relatively high coercive force. To meet such demand, permalloy (an Ni-Fe alloy), sendust (an FeAlSi alloy), an amorphous alloy, an FeRuGaSi alloy, etc. are recently proposed (Japanese Laid-open Patent Application No. 64-8604. An Fe-Si alloy (Japanese Laid-open Patent Application No. 59-78503, an Fe-C alloy, an Fe-Pt-C alloy (Japanese Laid-open Patent Application No. 1-144603) are also disclosed as materials having a high saturation flux density.
However, various studies made on such conventional alloys have revealed that the permalloy, sendust, amorphous alloy and FeRuGaSi alloy have the problem that they have a low saturation flux density Ms, the Fe-Si alloy and Fe-C alloy have a difficulty in corrosion resistance, and the Fe-Pt-C alloy has the problem that it has a low thermal resistance.